1. Field of the Invention
The present disclosure generally relates to an ink jet printing head for use in an ink jet printing device, and more particularly to an ink jet printing head having a printed circuit board to supply power and transmit signals, such as an image data signal and a driving waveform signal.
2. Description of the Related Art
FIG. 14 shows an ink jet printing head according to the related art as an example. As shown in FIG. 14, in the ink jet printing head according to the related art, an image-data control circuit board 102 is arranged outside a printing head main part 101, and the printing head main part 101 and the image-data control circuit board 102 are connected together by a flexible printed circuit board 103.
Although not illustrated, a host board is arranged to generate a driving waveform and image data to drive a piezoelectric device (a driving element) for discharging an ink drop from a nozzle. The host board and the image-data control circuit board 102 include connectors mounted on the circuit boards, respectively. The connectors mounted on the host board and the connectors mounted on the image-data control circuit board 102 are electrically connected together via a twistable flat cable.
On the other hand, Japanese Laid-Open Patent Publication No. 2005-204927 discloses a capsule type medical device which is adapted to improve the efficiency of storage of a plurality of rigid circuit boards in an airtight container. The capsule type medical device includes a flexible printed circuit board which links together the rigid circuit boards in a series connection, and the flexible printed circuit board is mounted in the airtight container in a bent condition so that the adjoining rigid circuit boards thereof face each other.
In the ink jet printing head according to the related art shown in FIG. 14, the image-data control circuit board 102 is arranged outside the printing head main part 101, and it is necessary to secure the housing space of the image-data control circuit board 102 in an ink jet printing device. This will become an obstacle to miniaturization of the ink jet printing device.
The printing head main part 101 and the image-data control circuit board 102 are connected together by the flexible printed circuit board 103. When attaching the printing head main part 101 to a printing device or when exchanging the printing head main part 101, an assembly-line worker has to hold the printing head main part 101 and the image-data control circuit board 102 by both hands, and the workability is poor.
To improve the workability, the flexible printed circuit board 103 may be shortened to the size of several millimeters and the image-data control circuit board 102 may be housed in the printing head main part 101. However, the shortened flexible printed circuit board 103 will be difficult to bend, and the original flexibility of the flexible printed circuit board 103 will be lost.
Moreover, a mechanical stress is generated in the printing head main part 101 at a time of connection of a twistable flat cable thereto and concentrated onto the fixed portion of the image-data control circuit board 102. At this time, the image-data control circuit board 102 may be curved or deformed. In such a case, cracks in the soldered parts of the image-data control circuit board 102 are likely to take place.
In the capsule type medical device disclosed in Japanese Laid-Open Patent Publication No. 2005-204927, the flexible printed circuit board is mounted in the capsule type medical device in a bent condition so that the adjoining rigid circuit boards may face each other. There is no need to secure the housing space of connectors in the capsule type medical device, and the efficiency of storage of the rigid circuit boards in the airtight container can be improved.
However, the arrangement of the capsule type medical device described above does not serve to improve the workability of assembling an ink jet printing head into an ink jet printing device, and does not function to prevent the cracks in the soldered parts of a printed circuit board from occurring during the assembling work.